Device for folding and locking the corners of a folding box blank



Jan. 5, 1960 c. J. PIERCE, JR 2,919,633

DEVICE FOR FQLDING AND LOCKING THE CORNERS OF A FOLDING BOX BLANK Filed May 2, 1958 v Sheets-Sheet 1 2'3 25 22 25 L 23 k 22 2 0 2 24 a0 22 I 25 L3 25 W 25 25 IN V EN TOR. Ches fer J Pierce, Jr.

BY M W ATTORNEY Jan. 5, 1960 c J. PIERCE, JR 2,919,633 DEVICE FOR FOLDING AND LOCKING THE CORNERS OF A FOLDING BOX BLANK Filed May 2, 1958 7 Sheets-Sheet 2 INVENTOR. Chesier J Pierce, Jr:

" ATTORNEY Jan. 5, 1960 c. J. PIERCE, JR 2,919,633

, DEVICE FOR FOLDING AND LOCKING THE CORNERS OF A FOLDING BOX BLANK 7 Sheets-Sheet 3 Filed May 2, 1958 IN V EN TOR. Chas/er J Pierce, Jr.

Jan. 5, 1960 c. J. PIERCE, JR 2,919,633

DEVICE FOR FOLDING AND LOCKING THE CORNERS OF A FOLDING BQX BLANK 7 Sheets-Sheet 4 Filed May 2, 1958 Fig. 5

IN V EN TOR. Cbesfer J Pierce, Jr:

(L ,4 Tram 5r c. J. PIERCE, JR DEVICE FOR FOLDING AND LOCKING ms Jan. 5, 1960 CORNERS OF' A FOLDING BOX BLANK 7 Sheets-Sheet 5 Filed May 2, 1958 6 INVENTOR. I (hes/er J. Pierc e, Jr.

6. 4d ATTORNEY DEVICE FOR FOLDING AND LOCKING THE CORNERS OF A FOLDING BOX BLANK -J an. 5,1960 I c-J. PIERCE, JR 2,919,533

Fil ed May 2, 1958- 7 Sheets-Sheet 6 k I! m Fig. 7 INVENIOR.

Chesfer J Pierce, Jr. BY

A rromvzy Jan. 5, 1960 c. J. Pl DEVICE FOR FOLDING Filed'May 2. 195a CORNERS OF A FOLDING BOX BLANK ERcE, JR 2,919,633

AND LOCKING THE 7 Sheets-Sheet 7 Chesfer J. Pierce, Jr. BY I W '5. 19. 4441 ATTORNEY United States Patent DEVICE FOR FOLDING AND LOCKING THE COR- NERS OF A FOLDING BOX BLANK Chester J. Pierce, Jr., Palo Alto, Calif., assignor to Balj ak Corporation, Wilmington, Del., a corporation of Deraware Application May 2, 1958, Serial No. 732,480

7 Claims. (Cl. 93-51) This invention relates to improvements in devices for folding flat box blanks into box form and locking the corners of the box by inserting a lock fiap articulated to one end wall into a slot in the adjacent box wall over which the lock flap is folded in the process of assembly.

Devices are know for gluelessly forming and locking box corners by means of a plunger which forces the blank through a forming die. In the known device the plunger carries hook-shaped elements in its sides which open slits in the box walls, grasp the lock flap folded over the box wall and pull a portion of the lock flap to the inside of the box. The patent to Pagendarm 2,580,189 of December 25, 1951, discloses such a device and also illustrates a form of box corner construction in which the lock flap is provided with a locking tfp which is pulled by force through the cut in the box wall and then becomes a safety catch preventing accidental disengagement of the corner lock.

The box construction disclosed in the aforesaid patent has the advantage of being quite rigid and resistant to forces acting on the box wall from the outside by reason of an edge-to-panel engagement between the box wall comprising the locking cut and the box wall to which the lock flap is articulated. This construction prevents inward folding of the box wall beyond a 90 degree position with respect to the box bottom resulting in a box which is less troublesome in subsequent handling, such as filling and closing, than boxes in which walls are readily folded beyond the 90 degree position by forces acting on the outside of the walls.

The box corner forming and locking mechanism disclosed in the aforesaid patent cannot be used for lined boxes, since the hook-shaped projections on the plunger which reach through the box walls and pull the box flaps to the inside would pierce the liner and destroy the liquid tightness of the box.

The present invention provides a mechanism for folding box corners of the aforementioned type by positively forcing a portion of the lock flap through the respective cut in the side wall without, however, damaging a box liner in any way. Devices incorporating the present invention may also be employed for the forming and locking of unlined boxes and offer the advantage of a very simple plunger construction which requires no movable elements in the plunger itself.

These and various other features and advantages of the invention will appear more fully from the detailed description which follows accompanied by drawings showing, for the purpose of illustration, a preferred embodiment of the invention. The invention also resides in certain new and original features of construction and combination of elements hereinfater set forth and claimed.

Although the characteristic features of this invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention itself, its objects and'advantages, and the manner in which it may be carried out may be better understood Patented Jan. 5, 1960 Figure 4 shows the device of Figure 3 after insertion of a fiat box blank;

Figures 5 to 8 show successive stages of operation of the device leading to the formation of a box with locked corners in Figure 8.

In the following description and in the claims various details will be identified by specific names for convenience. The names, however, are intended to be generic in their application. Corresponding reference characters refer to corresponding parts in the several figures of the drawings. The drawings accompanying, and forming part of, this specification disclose certain specific details of the invention for the purpose of explanation of its broader aspects, but it is understood that the details may be modified in various respects without departure from the principles of the invention and that the invention may be incorporated in other forms than the one shown.

The blank A shown in Figure l is representative of the general style of blanks which may be assembled by machines incorporating the present invention, and it is to be understood that other specific forms may be assembled by the mechanism about to be described, a representative form of such other blanks being disclosed in the aforementioned Pagendarm Patent 2,580,189.

The blanl: A comprises a main or bottom panel 11 to which side panels 12 and 13 are articulated along bottom side fold lines 14 and 15.

End panels 16 and 17 are articulated to the bottom panel 11 along bottom end fold lines 18 and 19. Lock flaps 20 are articulated to the end panels along lock flap fold lines 21 and comprise an external locking cut 22 extending into the body of the lock flap from an outer edge.

Internal cuts 23 in the side panels 12 and 13 form deflectabletongues 24 which, when acted upon by a force applied at right angles to the board, are readily flexed out of the plane of the side panels 12 and 13, thus opening slits into which the lock flaps 20 may be swung.

The configuration of the cuts 22 and 23 is such that at least a portion of the cut 22 is in coincidence with at least a portion of the cut 23 when the box corner is squared. Furthermore, the shape of the cuts is such that a tip portion 25 of the lock flap 20 extends beyond the confines of the internal cut 23 as is clearly seen in Figure 2. This tip may be forced through the internal cut 23 from its original position overlying the outside of the side wall into a locking position in which it underlies the inside of the side wall to form a safety catch which prevents accidental disengagement of the edges of cuts 22 and 23.

The mechanism illustrated in Figures 3 to 8 performs the folding of the blank in a more or less conventional manner and performs the locking of the blank corners in a novel manner in such a way that a liner which may be adhered to the inside surface of the blank A will not be damaged by the elements which open the slits in the side walls and other elements which force the tips 25 through the internal cuts 23.

The blank folding and locking device basically comprises a plunger 26 movable through the throat or aperture 27 of a die 28.

The plunger 26 comprises a block 29 of substantially rectangular base outline. It is mounted on the lower end of a stem having a flange 31 for attaching the plunger to a suitable reciprocating head 3?. guided for straight line movement by a rod or track 33. The plunger is moved up and down by suitable power means (not shown).

The plunger block 29 has upright end walls 34 and 35 and upright front and rear walls 36 and 37. The front and rear walls are provided with knob-like projections 33 which are so located as to bear against the side panels of the box in a position to open the cuts when the side walls are urged against the front and rear walls of the plunger.

Recesses 39 extend into the body of the plunger be tween the knob-like projections and the corners of the plunger. These recesses are open at he bottom as clearly seen in Figure 3, but may be closed at the top.

The die 28 comprises a frame 40 supporting lateral die portions 41 which extend substantially parallel to the front and rear walls of the plunger and have freedom to move away from the plunger. For this purpose the frame 49 is provided with guideways 42 in which the ends of the lateral die portions are held. The lateral die portions are drawn together by springs 43 and the closest spacing between the lateral die portions is determined by abutments 44 at the ends of the guideways, against which abutments the lateral die portions rest.

Each lateral die portion 41 of the illustrated embodiment comprises a rail 45 to which elements 46, 47 are welded which define the shape of the die throat cesses 48 are opposite the knobs 38 and provide clearance for the knobs and those portions of the blank which are deflected by engagement with the knobs 33 when the plunger passes through the die.

The throat elements have curved shoulders 49 and 5% at the top for gradually folding the blank panels and flaps. The end elements 46 are slightly set back with respect to the central elements and have a front surface slanted towards the corners of the die aperture.

Further throat defining elements 51 are mounted opposite the end walls of the plunger and are shown in the illustrated example in the form of curved plates having a flared upper portion and a substantially vertical bottom portion. The end elements 51 are mounted on rods 52 pivoted in blocks 53. Springs 54 between the rails 45 and levers 55 clamped on the rods 52 by bolts 56 normally maintain the elements 51 in a position of minimum clearance with respect to the plunger. The end elements 51 may be deflected out of their normal position to provide enlarged clearance, in which event the end elements 51 and rods 52, together with the levers 55, til-t slightly against the action of the springs 54.

Alignment pins 56 and 57 are provided for lining up the box blank A with respect to the plunger 2? and the die.

Blanks A are placed over the die normally by a suitable blank feeder which is not shown in the drawings for the sake of clarity. Figure 4 shows the blank A properly lined up between the pins 56 and 57 at which moment the plunger begins to descend.

The descending plunger strikes the bottom panel of the blank and the shoulders 5i) of the central element 47 fold the side panels 12 and against the front and rear walls of the plunger. Figure 5 illustrates the position in which the side walls of the blank are upright. The knobs or projections 38 cause the wall panels to bow out slightly, thus opening the slits 23 in the side walls of the box about to be formed. The vertical edges 58 of the throat elements 46 flex the blank in a direction opposite to the action of the projections to open the slits still wider.

The lock flaps 20 which were first folded into sub stantial upri ht position with. respect to the end panels 3.6 and 17 by the end elements 51 are then guided by the slanted front surfaces of said elements into the opened slits 23 as shown in sequence in Figures 5 and 6.

Figure 7 shows the position in which the end walls as well as the side walls of the box are upright with respect to the box bottom. The leading edges of the lock flaps 20 are inserted into the slits in the side panels, but there is as yet no engagement between the cut edges 22 of the lock flap and a portion of the cut 23. The tip 25 of the lock flap still overlies the outside of the side panels of the box and must next be forced through the cut aperture 23 into a new position in which it underlies the inside of the side panels of the box.

This is accomplished by a mechanism best visible in Figures 7 and 8 actuated by elements best seen in Figure 6.

In the drawings only the mechanism acting on the near side panels 13 is visible, and it is understood that a similar mechanism is provided to act on the corner locks which engage the far side panel 12.

A pair of depending arms 59 is clamped to a pivot shaft 60 by means of bolts 61. The shaft 69 is pivoted in a bearing block 62 on the underside of the lateral rail 45 so as to be movable with it. At its lower end each arm 59 carries a finger 63 opposite the recesses 39 of the plunger.

The fingers are normally retracted beyond the rectangular outline of the plunger base, so as to clear not only the plunger, but also a box on the plunger. Figure 7 shows the arms 59 in this position.

The arms may be swung into a projected position in which the fingers 63 extend into the recesses 39 of the plunger, as shown in Figure 8. In doing so the fingers 63 engage a portion of the lock flaps sufliciently close to the tips 25 to force these tips, by flexing of the stock, from the outside of the box to the inside, thus engaging the locking edges and providing the aforementioned safety catch. The projecting motion of the fingers occurs in the opposite sense to the freedom of the lateral rails 45 to move away from the plunger into a position of greater clearance.

The actuating mechanism which swings the arms from the position shown in Figure 7 into the position shown in Figure 8, and which subsequently retracts the fingers to the position of Figure 7, comprises a lever 64 mounted on the pivot shaft 64 in the nature of a bell crank. Depression of the lever 6 causes the arms 59 to swing into the position of Figure 8.

A depressible actuator 65 having aflat head 66, normally raised by a spring 67, is linked to the lever 64 at 68. The head 66 is adapted to be engaged by the ends 69 of arms 70 mounted on the plunger stem 30.

In the position shown in Figure 7 the ends 69 of the arms 74) are about to strike the heads 66 of the actuators 65. In the position shown in Figure 8 the actuators are fully depressed, the restoring springs 67 are compressed and the plunger has reached the lowest point of its stroke. At this point the bottom edges 71 of the end elements 51 are slightly above the top edges of the box to strip the box from the plunger during the subsequent return stroke of the plunger. In the position shown in Figure 7 the bottom edge 71 of the elements 51 is still slightly below the top edge of the box.

As the plunger returns to its top position, the arms 70 release the actuator head 66 and the fingers 63 return to their outermost position. The set-up box is stripped from the plunger and the device is in condition to receive a new blank as soon as the plunger is withdrawn from the die.

What is claimed is:

1. A device for folding and locking the corners of a folding box blank comprising, a front wall, a rear wall, and opposite end walls with lock flaps to be folded over, and partially inserted into, curved slits in the front and rear walls, the slits forming tongues in the walls, said lock flaps including a locking projection extending beyond the confines of said tongue, which projection is to be forced from a position overlying the respective wall panel.

into an underlying position in the completed box, the de vice comprising, a plunger having a substantially rectangular bottom area, upright end walls, and upright front and rear walls, said front and rear walls being provided with knob-like projections in a position to bear against a portion adjacent a slit of a blank erected about said plunger, said plunger further having recesses extending into the body of the plunger between said'knob-like projections and the corners of the plunger, said recesses being open at the bottom; a'die through which the plunger is movable, said die having lateral portions extending substantially parallel to the front and rear walls of the plunger and end portions substantially parallel to the end walls of the plunger, considering plunger and die in plan view, each of said lateral portions comprising a lateral rail having throat elements thereon defining a die throat through which said plunger passes, said throat elements being recessed opposite said knob-like projections on the plunger for clearance of the projections with respect to the die during passage of the plunger through the die, projectible and retractable finger elements on said lateral rails in line with the recesses inthe plunger, said finger elements being located to bear against the locking projections of the blank when the plunger is in its position of deepest entry into the die, spring means for retracting said finger elements to a position outside the rectangular outline of the plunger bottom, a depressible actuator mounted on each of said rails for projecting the respective finger elements into a position inside the rectangular outline of the'plunger bottom into the recesses upon depression of the actuator, and means for mounting the lateral rails for movement towards and away from each other to permit temporary widening of the throat of the die; and an arm on said plunger for engaging and depressing said actuators near the end of the down-stroke of the plunger to force the locking projections into said underlying position, said arms having a reach sufficiently large to strike said actuators in the position in which the throat of the die is narrow as well as in the position in which the throat of the die is temporarily widened.

2. A device for folding and locking the corners of a folding box blank comprising, a front wall, a rear wall, and opposite end walls with lock flaps to be folded over, and partially inserted into, curved slits in the front and rear walls, the slits forming tongues in the walls, said lock flaps including a locking projection extending beyond the confines of said tongue, which projection is to be forced from a position'overlying the respective wall panel into an underlying position in the completed box, the device comprising, a plunger having a substantially rectangular bottom area, upright end walls, and upright front and rear walls, said front and rear walls being provided with tive finger elements into a position inside the rectangular outlineof the plunger bottom into the recesses upon depression of the actuator, a frame supporting said lateral rails with freedom of movement towards and away from knob-like projections in a position to bear against a portion adjacent a slit of a blank erected about said plunger, said plunger-further having recesses extending into the body of the plunger between said knob-like projections and the corners of the plunger, said recesses being open at the bottomya die through which the plunger is movable, said die having lateral portions extending substantially parallel to the front and rear walls of the plunger and end portions substantially parallel to the end walls of the plunger, considering plunger and die in plan view, each of said' lateral portions comprising a lateral rail having throat elements thereon defining a die throat through which said plunger passes, said throat elements being recessed opposite said knob-like projections on the plunger for clearance of the projections with respect to the die during passage of the plunger through the die,,projectible and retractable finger elements underneath said lateral rails in line with the recesses in the plunger, said finger elements being located to bear against the locking projections of the blank when the plunger is in its position of deepest entry into the die, spring means for retracting said finger elements to a position outside the rectangular outline of the plunger bottom, a depressible actuator mounted on each of said rails for projecting the respeceach other to permit temporary widening of the throat of the die; stop means for arresting said rails in a normal position in which the throat is narrow, and spring means for urging said rails against said stop means; and an arm on said plunger for engaging and depressing said actuators at the end of the downstroke of the plunger to force the locking projections into said underlying position, while simultaneously tending to move said rails apart, said arms having a reach sufiiciently large to strike said actuators in the position in which the throat of the die is narrow as well as in the position in which the throat of the die is temporarily widened.

3. A device for folding and locking the corners of a folding box, the device comprising, a plunger having a substantially rectangular base area, end walls substantially vertical with respect to the base area, and front and rear walls substantially vertical with respect to the base area and at right angles to said end walls, said front and rear walls having projections on them at a distance from the corners, said front and rear walls being further provided with recesses between-said projections and the respective nearest corner; a die through which said plunger is movable, said die having lateral portions. extending substantially parallel to the front and rear walls of the plunger, and end portions substantially parallel to the end walls of the plunger, considering plunger and die in plan view, each of the lateral portions being recessed opposite said projections on the plunger for clearance of the projections with respect to the die during passage of the plunger through the die, projectible and retractable finger elements on said lateral portions in line with the recesses of the plunger, said finger elements being normally in a retracted position in which they lie outside the rectangular base area of the plunger, considering the device in plan view, and being projectible into a position in which they project into said plunger recesses inside said rectangular base area, biasing means for normally maintaining the finger elements retracted; means operable in response to the movement of the plunger for projecting said finger elements into the recesses of the plunger, as the plunger passes said fingers; and means for mounting said lateral die portions for movement away from the plunger, said mounting means including stop means for arresting said lateral portions in a position in which the throat of the die is narrow, and spring means for urging said lateral elements towards the narrow-throat-position, said lateral portions being movable against the action of said spring means in a direction opposite to the motion of the finger elements into their projected position to permit temporary enlargement of the throat of the die as the plunger passes through the die and the fingers are projected.

4. A device for folding and locking the corners of a folding box, the device comprising, a plunger having a substantially rectangular base area, end walls substantially vertical with respect to the base area, and front and rear walls substantially vertical with respect to the base area and at right angles to said end walls, said front and. rear walls having projections on them at a distance from the corners, said front and rear walls being further provided with recesses between said projections and the respective nearest corner; a die through which said plunger is movable, said die comprising, a pair of lateral rails having throat elements thereon extending substantially parallel to the front and rear walls of the plunger, said throat elements being recessed opposite said projections on the plunger for clearance of the projections with respect to the die during passage of the plunger'past said throat elements, means for supporting said lateral rails for movement toward, and away from, the path of the plunger including spring means for urging said lateral rails toward the position in which said throat elements define a narrow die passage, said lateral rails being displaceable in a direction away from the path of the plunger against the action of said spring means for temporary enlargement of the throat of the die, projectible and retractable finger elements mounted on, and underneath, said lateral rails in line with said recesses in the plunger, said finger elements being normally retracted to lie out side the rectangular base area of the plunger, considering the device in plan view, and being projectible into a position in which they project into the plunger recesses within the rectangular base area, biasing means for normally maintaining the finger elements in their retracted position; and means operable in response to the movement of the plunger for projecting said finger elements into the recesses of the plunger as the plunger passes said fingers.

5. A device for folding and locking the corners of a folding box, the device comprising, a plunger having a substantially rectangular base area, end Walls substantially vertical with respect to the base area, and front and rear Walls substantially vertical with respect to the base area and at right angles to said end walls, said front and rear walls having projections on them at a distance from the corners, said front and rear walls being further provided with recesses between said projections and the respective nearest corner; a die through which said plunger is movable, said die comprising, a pair of lateral rails having throat elements thereon extending substantially parallel to the front and rear walls of the plunger, said throat elements being recessed opposite said projections on the plunger for clearance of the projections with respect to the die during passage of the plunger past said throat elements, means for supporting said lateral rails for movement toward, and away from, the path of the plunger including spring means for urging said lateral rails toward the position in which said throat elements define a narrow die passage, said lateral rails being displaceable in a direction away from the path of the plunger against the action of said spring means for temporary enlargement of the throat of the die, projectible and retractable finger elements mounted underneath said lateral rails in line with said recesses in the plunger, said finger elements being normally retracted to lie outside the rectangular base area of the plunger, considering the device in plan view, and being projectible into a position in which they project into the plunger recesses within the rectangular base area, biasing means for normally maintaining the finger elements in their retracted position, a depressible actuator mounted on each of said rails for projecting the respective finger elements; and arms on said plunger for engaging and depressing said actuator near the end of the downstroke of the plunger, said arms having a reach sufiiciently large to strike said actuator in the position in which the lateral rails are in their narrow-throat-position as well as in the position in which the lateral rails are outwardly displaced to enlarge the throat of the die.

6. A box folding and locking device particularly for folding and locking the corners of a folding box having a box bottom, box sides, and corner lock flaps on certain sides insertable into slots in other box sides, the device comprising, a plunger having a substantially rectangular base area substantially equal in size to the box bottom, the plunger further having end surfaces substantially vertical with respect to the base area, and front and rear surfaces substantially vertical with respect to said base area and at right angles to said end surfaces, said front and rear surfaces having projections on them at a distance from the corners, said projections being adapted to engage and flex certain portions of the box sides, said front and rear surfaces being further provided with recesses between said projections and the respective nearest corner; an open-bottom die through which said plunger is movable, said die having lateral portions extending substantially parallel to the front and rear surfaces of the plunger, and end portions substantially parallel to the end surfaces of the plunger, considering plunger and die in plan view, each of the lateral portions being recessed opposite said projections on the plunger for clearance of the projections with respect to the die during passage of the plunger through the die; finger elements mounted on said die with freedom of projecting and retracting motion into and out of the recesses of the plunger; biasing means for normally maintaining the finger elements in a retracted position in which they lie outside the rectangular base area of the plunger, considering the device in plan view; means operable in response to the movement of the plunger relatively to the die for projecting said finger elements beyond said projections to flex other portions of the box into the recesses of the plunger as the plunger passes said fingers; and means on said die for engaging the top edge of the box and detaining the box in the die against the retracting motion of the plunger, said last named means being mounted to engage the top edge of the box when said finger elements are in projected position.

7. A box folding and locking device particularly for folding and locking the corners of a folding box having a box bottom, box sides, and corner lock flaps on certain sides insertable into slots in other box sides, the device comprising, a plunger having a substantially rectangular base area substantially equal in size to the box bottom, the plunger further having end surfaces substantially vertical with respect to the base area, and front and rear surfaces substantially vertical with respect to said base area and at right angles to said end surfaces, said front and rear surfaces having projections on them at a distance from the corners, said projections being adapted to engage and flex certain portions of the box sides away from the plunger, said front and rear surfaces being further provided with recesses between said projections and the respective nearest corner; an open-bottom die through which said plunger is movable, said die having lateral portions extending substantially parallel to the front and rear surfaces of the plunger, and end portions substantially parallel to the end surfaces of the plunger, considering plunger and die in plan view, each of the lateral portions being recessed opposite said projections on the plunger for clearance of the projections with respect to the die during passage of the plunger through the die; finger elements mounted on said die with freedom of projecting and retracting motion into and out of the recesses of the plunger; biasing means for normally maintaining the finger elements in a retracted position in which they lie outside the rectangular base area of the plunger, considering the device in plan view; means timed with the plunger for projecting said finger to flex other portions of the box towards the plunger and into the recesses of the plunger when the plunger is opposite said fingers; and means on said die for engaging and detaining the box in the die against the retracting motion of the plunger, said last named means being mounted to engage the box when the box is opposite said finger elements and said elements are in projected position.

References Cited in the file of this patent UNITED STATES PATENTS 2,580,189 Pagendarm Dec. 25, 1951 2,627,791 Ringler Feb. 10, 1953 2,635,512 Harker Apr. 21, 1953 2,832,270 Pierce et al Apr. 29, 1958 

